Control device for the percussion pin of a projectile fuse



July 28, 1959 A. VOLAND CONTROL DEVICE FOR THE PERCUSSION PIN OF APROJECTILE FUSE Filed NOV. 29, 1955 face.

' CONTROL DEVICE FOR THE PERCUSSION PIN OF A PROJECTILE FUSE AndreVoland, Zurich, Switzerland Application November 29, 1955, Serial No.549,830

Claims priority, application Switzerland December 6, 1954 1 Claim. (Cl.102-76) The object of-the present invention is a control device for thehammer of a projectile fuse provided with muzzle safety and proximaltrajectory safety devices and self- "destruction devices and comprisinga percussion pin and a percussion spring disposed coaxially to thehammer.

The control device according to the invention is characterized in thatit comprises a dash-pot regulating the motion of the percussion pin anddisposed coaxially to said pin, in that the buffer fluid in thisdash-pot is a silicone having a chain structure containing Si(CH groupsand a viscosity which remains substantially constant within a'wide rangeof temperatures, and in that it comprises a spring disposed coaxially tothe percussion pin and actuating the mobile member of the dash-pot,

which spring is fastened by locking means controlled by an accelerationwhich occurs at least when the projectile is moving, andlocking meansdepending on the displace- "1 the body of the fuse which is screwed bymeans of 'threaded portion 2 in the projectile, which is not shown.

3 is the percussion pin of the hammer the point of which is visible at4. An inner member 5 is axially screwed into the body 1 by means ofholes 6 provided in its rear The point4 of the percussion pin isdestined to slide in an axial hole 7 of this member 5.

The fore end 8 of the percussion pin shaft is in contact with an elasticdisk 9 arranged at the bottom of a inder 36 constitutes a chamber inwhich a piston 37 can slide axially, a compression spring 38 beingfitted inside this piston and resting on the one hand against the bottomof the part 33, and on the other, against the bottom of the piston 37 inorder to pull the latter in the downward direction in Fig. 1. Threeradial holes 39, spaced 120 apart, are provided in the lateral wall ofthe part 36 and in each of these a ball 43 is partially engaged. In theposition of the components shown in the drawing, the

three balls 49 constitute a stop preventing piston 37 from movingdownwards in spite of the action of spring 38.

. The diameter of the balls is such that on the inside they rest againstthe pin 3 of the hammer, whilst on the outside they are prevented fromleaving their holes 39 by the skirt of the hollow piston 34.

-'Ihe space circumscribed by member 33, cylinder 36 i are Patented July28, 1959 and piston 37 forms a chamber the axis of which is that of thefuse, and which is filled with a mass 42 made of a silicone grease oroil having a linear or cyclic chain structure containing the groupsSi(CH Each terminal point of the chain is effected by three methylgroups united to the silicon atom. The viscosity of silicones of thistype is an exponential function of the number of groups. It is thuspossible to obtain the desired viscosity by judicious choice of thenumber of groups. It is also possible to obtain a silicone oil or greasehaving a given viscosity, by mixing silicones of diiferen't viscosities.

The pin 3 of the hammer is provided in its lower portion, with a part oflarger diameter 24 which is capable of sliding in an axial hole 25 ofthe cylinder 36. The upper part of member 5 is provided with a radialcylindrical hole 26, in which is fitted a piston 27, provided with aslot 28 over part of its length. The extremity of the percussion pin 3,comprised between the'part of larger diameter and the point 4, passesthrough this slot 28, the width of which is such that the piston 27prevents the percussion pin from moving further down than the positionshown in Fig; 1 as long as this percussion pin is engaged in the slot28.

The open end of the cylindrical hole 26 is provided with a stopping plug29, pierced by a calibrated hole 30. The part of this cylindrical hole26 which is comprised between the piston 27 and the plug, forms achamber which is filled with a mass 31, of the same nature as the mass42.

The upper part of the chamber containing the mass 42 is provided with acalibrated hole 43 passing through member 33 and through which thischamber can communicate with a hollow space comprised between 33 and 1.

The operation of the device according to Fig. 1 is as follows:

The components are shown in the position they occupy before the shot isfired. The left-hand extremity of the piston 27, on the slotted side, isengaged in a notch 4-1, provided in the wall of the piston 34, whichprevents this piston from following the pull of the spring 35. At themoment of the firing of the shot, the projectile is made to rotate bythe rifling of the barrel of the weapon, and, owing to the effect ofthis rotation, the piston 27 which is arranged eccentrically in relationto the axis of the fuse, is urged away from this axis by the centrifugalforce. Owing to this, it compresses the mass 31 which slowly escapesthrough the calibrated hole 30. The calibration of this hole 30 ischosen in such amanner that the piston 27 ceases to block the percussionpin (by cooperation of the edges of the slot 28 with the lower extremityof the enlarged part of the pin 3) after a lapse of time which is suchthat the muzzle safety as well as the proximal or immediate trajectorysafety is assured. Any premature ignition of the discharge is thusprecluded. As soon as the piston 27 has moved sufliiciently to the rightin Fig. l to release the percussion pin, the fuse is ready to operate bypercussion against any kind of obstacle so as to produce the ignition ofthe charge by means of the point 4 of the percussion pin. In case ofpercussion of the fuse against an obstacle, the thin bottom 32 of thehole 11, which constitutes the fore end of the fuse is driven in andforced axially in the downward direction on the drawing, taking the part10 and the fore end 8 of the percussion pin with it. The action of thepoint 4 of the percussion pin takes place immediately.

If within a certain time interval, which is determined in advance, thefuse has encountered no obstacle, it must ensure the self-destruction ofthe projectile as is well known. This is efiected in the followingmanner:

'In the course of this movement, the piston. 27 begins by releasing thepiston 34, owing to the fact that it leaves the notch 41. From thatmoment the piston 34 rises under the action of the spring 35 and drivesthe material 42 through the calibrated hole 43 in the part 33. The

' quantity of the material 42, the force of the spring 35 and thedimensions of the calibrated orifice 43 are calculated in such a mannerthat the lower part 44 of the piston 34 only uncovers the orifices 39 atthe moment when 'selfdestruction is to take place. 1

From the moment when piston 34 uncovers orifices 39, the balls '40,under the action of the centrifugal force exerted on them as the resultof the rotation of the projectile, escape through these orificestowards.

the outside, into the space comprised between parts 33 and 36, whencethey free piston 37. Spring 38' then drives piston 37 towards the bottomand the ignition occurs to effect the self-destruction of theprojectile.

It may be seen from the above that the described deviceenables theself-destruction of the projectile and the muzzle and proximal orimmediate trajectory safety to be obtained in a simple and pure manner.The adjustment of the time intervals for these two functions may be madeeasily and with precision by giving to the calibrated hole 30 theappropriate dimensions. The consistency of the silicone greases preventsany leakage through the calibrated holes 21 and 30 whilst thedevices arekept in stock. The chemical composition of fuse, a weight 62 providedwith a slot 63 in which the lower extremity of the pin 3 of the hammeris engaged. This part 62, with its slot 63, cooperates with the enlargedpart 24 of the pin 3, as has been described withrespect to the part 27and its slot 28 in the preceding jectile is accelerated, i.e., as longas it is in the barrel of the weapon. Owing to the rotation of theprojectile, the part 62 is pulled in the outward direction, but it isunable to move as long as the part65 is engaged in the slot "64. Owingto the effect of this same rotation, the stud 57 is urged in the outwarddirection by the centrifugal force, and the split ring 58 tends to beopened. As

long as the part 47 is strongly forced against this ring these massesprotectsthe device from any undesirable,

chemical action. The quasi constancy of their viscosity,

within a range of temperatures of plus or minus 50 in relation to thenormal, greatly contributes towards ensurmg a sure operation.

It will be remarked that the piston 34, with its cali.

owing to the acceleration of the projectile, the ring cannot open andretains the stud 57 in its place. When this acceleration ceases, i.e.,as soon as the projectile has left the barrel of the weapon, the part 47is urged in the upward direction under the action of the ring 58 whichopens under the action of the centrifugal force. This ring is disengagedfrom the parts 46 and 47, and the stud 57 escapes in the outwarddirection into a chamber 66'of the body 1. -The stud 57 was engaged in acalibrated hole 67 of the part 48. The material 68 in the brated hole 43and the material 42, constitutes a dashpot. As for the muzzle andproximal trajectory safety it is ensured by means of the dash-potconstituted by the piston 27, the calibrated hole and the material 31.

In the'second embodiment according to Fig. 2, there is only one dash-potensuring the two functions of the muzzle andproximal trajectory safetyand of self-destruction. The parts which are identical with those of thetwo preceding embodiments are indicated -by the same references.

The interior of the body 1 of thefuse is provided with i an axialcylindrical chamber 45, in which are arranged two cylinder sections 46,47. The member 5 is provided with a cylindrical extension 48 extendinginside the cylinder sections 46, 47 in order to fix to the body 1 amember 49, inside which is a cylindrical-chamber 50 through which thepercussion pin 3 of the hammer passes longitudinally. A compressionspring 51 arranged inside the chamber 50 surrounds the pin 3, andresting against the upper closed portion of this chamber, pulls in thedownward direction (in Fig. 2) a ring'52 which can slide axially in thischamber.. This ring is locked by two weights 53, fitted in radial holes54 of the part 49. These welghts are in contact on the inside with thepin 3 of the hammer, and are prevented from leaving their hole 54 in theoutward direction by the skirt of a hollow piston 55 which can slide, onthe one hand, on the part 49, and on the other, in the cylindricalchambenlimited by the parts 48. A compression spring 56, resting againstthe member 5, pulls the piston'55 in the upward direction in Fig. 2.This piston is locked, in the position of the components shown, by astud 57, fitted in a radial hole of the part 48 and which is held inplace, on the inside, by a split metallic ring 58, provided between thetwo parts 46, 47 and around the exterior wall of the part 48. The parts46, 47 are chamfered so as to offer the shape of a truncated cone attheir extremities which are in contact with the ring 58. An axialclearance 59 exists bet-ween. theupper extremity of the part 47 and theupper bottom of the chamber 45.

The member 5 is provided with a radial hole 61, in which isfitted,eccentri'cally in relation to the of the chamber comprised between 48and 49 above the piston 55, can then escape through this hole into thechamber 66. Then the piston 55, which is now no longer locked by thestud 57, drives the material'68 through the hole 67 and at the same timethrough calibrated orifices 69 provided in the upper part of the chambercontaining this material. When the piston reaches and moves on beyondthe upper edge of the hole 67, the material 68 can no longer escapethrough this hole; it can only continue to escape by the calibratedholes 69. It is at this instant that the part 65 ceases to retain thepart 62, which under the action of the centrifugal force, starts to movein the outward direction and ceases to lock the shaft of the percussionpin. In this way the muzzle and proximal trajectory safety is secured.It will be remarked that the hole 67 is much larger than the holes 69,which is easy to understand, because the time required to secure themuzzle and proximal trajectory safety ,is much shorter than the timeinterval at the end of which self-destruction must occur. From themoment when the part 62 has released the shaft of the percussion pin,the ignition can take place; as may be easily understood, if the pointof the fuse encounters an obstacle, there is then nothing to prevent theshaft from moving downwards when 32 If ignition does not take placeowing to. percussion of the fuse, the moment arrives when the lowerextremity 65 of the piston 55 uncovers the holes 54, whichallows theweights to move in the outward direction for a distance which issufiicient to allow it to no longer lock the ring 52 and the spring '51.At this moment, the spring 51 drives the ring in the downward direction,this ring strikes the enlarged part 24 of the shaft of the percussionpin, and the point 4 of the latter produces the ignition.

In the embodiment according to Fig. 2, the mass 68 is preferably of thesame type as the one indicated above with respect to Fig. l. V

The invention, although illustrated in the two embodiments described bythe case of rotating projectiles,

is not limited to this type of projectile. The locking means controlledby centrifugal force (27, 41, 57) could actually be replaced by lockingmeans controlled by the linear acceleration (instead of the angularacceleration) occurring at the time the projectile is fired.

What I claim is:

A control device, for the hammer of a projectile fuse provided withmuzzle and proximal trajectory safety and self-destruction devices,comprising a percussion pin displaceable by said hammer, a percussionspring operatively associated with said pin for displacing the same toeffect a detonation, a dash pot including a mobile member andoperatively associated with said pin for regulating the displacementthereof, a bufier fluid in said dash pot and being constituted by asilicone having a chain structure containing Si(CH groups and asubstantially constant viscosity despite temperature changes, a furtherspring operatively associated with said dash pot for actuating themobile member thereof, first locking means for locking the percussionpin in position and the mobile member in position against the action ofsaid further spring and releasing the mobile member in response torotation of the projectile, second locking means operatively associatedwith said mobile member and said percussion spring for controlling thepercussion spring and releasing the same to actuate the percussion pinin response to the displacement of said mobile member, said dash potdefining axial ancl radial calibrated orifices, and a displaceable studincluded in the first locking means and in the radial orifice forlocking the mobile member in position, a displacement of the studenabling displacement of the mobile member and escape of the buflerfluid through the orifices, a predetermined displacement of the mobilemember closing oif the radial orifice and preventing escape of fluidtherethrough.

References Cited in the file of this patent UNITED STATES PATENTS570,065 Smith Oct. 27, 1896 972,425 Wilson et a1 Oct. 11, 1910 2,405,653Honger Aug. 13, 1946 2,407,037 Sowa Sept. 3, 1946 FOREIGN PATENTS245,766 Great Britain Jan. 4, 1926 742,598 France Ian. 4, 1933

